1. Field of the Invention
The present invention relates to a scanning carriage assembly for use in an electrophotographic machine employing a charge coupled device sensor or similar reproducing and document scanning apparatus. In particular, it relates to the structural support of the carriage assembly and especially to the scanner drive and stabilizing cables incorporated within the assembly to provide stabilizing tension to the scanner assembly during reciprocal scanning motion. The scanning carriage assembly is that type of scanning apparatus provided for reproducing original documents in a reproduction machine. The optical scanner utilized is a charge coupled device (CCD sensor) which is used in place of more bulky conventional optics in the prior art document scanners. The prior art has typically demonstrated the use of the combination of lens optics and mirrors in order to achieve translation of the image of an illuminated object placed on a document platen glass to an imaging station where the image is exposed unto a sensitized photoconductor.
The application and use of the CCD sensor as a scanner provides a way to greatly reduce dimensional space requirements taken up previously by prior art by optical scanning apparatus because of the relative small size of the CCD sensor assembly. The means of reducing the scanner size is demonstrated in the present invention and when combined with other new electronic technology allows the image of the source material to be processed and developed in different efficient ways. For example, the resultant image may be converted into a train of electronic pulses which are reconstructed on a cathode ray tube which may be remotely situated and then projected directly unto a photoconductor surface where conventional copier processes are used for image development and transfer of the image unto copy paper.
A typical CCD scanner is partially comprised of a scanner assembly having an optical path with dual mirrors which are arranged compactly so that multiple reflections are generated between the two mirrors. There may be typically six reflections of an image between the two mirrors which necessitates maintaining a strict unyieldable structural relationship between the two mirrors. The need for a rigid vibration-free relationship between the CCD scanner and the mirrors becomes especially critical during translating motion of the scanner carriage.
Presently, a copending application serial number 378,038, entitled Folded Beam Adjustment and filed May 14, 1982 by the inventor, Hugh Dannatt, of the present invention demonstrates the solution of certain problems relating to obtaining a direct illuminated image by adjusting the CCD lens unit to the cooperating, compactly-arranged mirrors without physically adjusting the mirrors. Avoidance of disturbing this particular mirror arrangement is highly desirable because of the inherent difficulty in aligning and rigidity holding mirrors designed and intended to generate multiple reflections. These difficulties are greatly compounded because of the mounting of the mirrors in a carriage which is slidably mounted on rails and supported in structure comprising the framework of a machine which has other mechanisms additionally mounted to such framework thereby causing various vibrations or shocks which could adversely effect the reproduction of an image.
2. Description of the Prior Art
U.S. Pat. No. 4,332,460 issued to Costanza describes the problems associated with optical scanning systems which employ lamps, mirrors and reciprocating carriages. The problems described are typical of such equipment and the subject patent goes into detail in providing additional mechanism in the form of shock absorbers to reduce impact of stopping forces felt upon the carriage assembly, lamps and mirrors. The system and auxiliary mechanisms described is typical of the prior art in that substantial space is required to suspend, mount and house the entire scanner. The specification of the subject patent also discloses use of dual driving cables attached to opposing lateral ends of the optical scan carriages and a dash pot is utilized to help reduce the impact of dynamic forces at the ends of the reciprocating carriage motion. In addition, the embodiment incorporates the use of spiral grooves in the cable mounting drums which dominate the lateral positions of the cables as they move laterally during carriage motion.
In view of the prior art, the present disclosure presents a stabilizing means for minimizing dynamic effects induced by variations in the connection of the drive components for optical scanners. The continuous looped carriage drive members utilized in the present disclosure are arranged in a parallel relationship to each other and the scanner guide members. The cables remain parallel to the guide members during all phases of the scanning functions. In addition, the carriage drive members in the form of flexible drive members utilized in the present arrangement are not subject to diagonal and tensile load variations due to spiral grooves in the driving member drums which otherwise force side-wise tracking of the prior art drive members such as cables. Therefore, the present disclosure provides a stable, drive system for an optical document scanner regardless of the effects of variations in the location of the center of gravity of the component parts or differences in tensions of driving members due to tolerances, acceleration or deceleration.